Page 76 - DCAP402_DCAO204_DATABASE MANAGEMENT SYSTEM_MANAGING DATABASE

Unit 4: Advanced SQL

The result of the expression is as follows: Notes

Find all customers who have either an account or a loan (but not both) at the bank

Select cust_name
From (depositor natural full outer join borrower)
Where account_no is null or loan_no is null

Task Role of natural join in DBMS.

Lab Exercise Create a table with 6 column and enter at least five values in the table and do
this exercise:
1. select top 40% from table
2. select column1, column2 and column3 simultaneously from table (joint all)

4.6 Summary

 SQL also has a good programming level interfaces.
 The SQL supports a library of functions for accessing a database.
 These functions are also called the Application Programming Interface (API) of SQL.
 The advantage of using an API is that it provides flexibility in accessing multiple databases
in the same program irrespective of DBMS, while the disadvantage is that it requires more
complex programming.

4.7 Keywords

Full Outer Joins: The full outer join type is a combination of the left and right outer-join types.
Inner Joins: Inner joins return all rows from multiple tables where the join condition is met.
Natural Joins: Natural join combines two tables based on their common columns i.e. columns
with the same name.
Nested Query: A query inside a query is called as nested query.
Subqueries: Subqueries are similar to SELECT chaining. While SELECT chaining combines
SELECTs on the same level in a query, however, subqueries allow SELECTs to be embedded
inside other queries.
Views: A view is a virtual table, which does not actually store data.

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